The present invention relates to a taper roller bearing lubricating structure in a transmission, and more specifically to a taper roller bearing lubricating structure for supporting an output gear in an automatic transmission for motor vehicles.
A Japanese Patent Kokai Publication No. H2(1990)-89871 shows a conventional lubricating structure for an automatic transmission.
In this structure, as shown in FIG. 7, a taper roller bearing 36 rotatably supports, on a partition wall 45, an output gear 31 which endures a great torque on the output side of a planetary gear system. Each of tapered rollers 32 and 33 can support a load acting in the radial direction with its rolling contact surface 32a or 33a along a line instead of a point as in a ball bearing. A load in a thrust direction can be supported by the rolling contact surface 32a or 32b and the end surface 32b or 33b of each tapered roller 32 or 33 together with an inner lace 39 contacting with these surfaces.
An oil passage 30 is formed in an outer race 40, for lubricating the tapered rollers 32 and 33.
This conventional lubricating structure has an oil passage 46 specifically formed in the partition wall 45, for lubrication of the taper roller bearing 36. However, according to our findings, the lubrication for the tapered rollers 33 still tends to be insufficient, specifically in the end surfaces 33b of the tapered rollers 33 on the side remoter from the output gear 31.
It is an object of the invention to provide a taper roller bearing lubricating structure capable of supplying sufficient lubricating oil to tapered rollers without complicating the manufacturing process.
It is another object of the invention to provide a taper roller bearing lubricating structure capable of supplying sufficient lubricating oil specifically to tapered rollers remote from an output gear without complicating the manufacturing process.
According to the present invention, a lubricating structure for an automatic transmission comprises:
an output gear having a gear portion for delivering an output rotation of the automatic transmission, and a hollow boss;
an inner rotating shaft disposed inside the boss of the output gear and formed with a lubricating oil passage;
a taper roller bearing disposed around the boss of the output gear;
an outer support surrounding and supporting the taper roller bearing; and
a dam forming an oil reservoir for storing a lubricating oil from the oil passage in the rotating shaft, the oil reservoir being formed radially between the boss of the output gear and the outer support, and axially between the dam and the taper roller bearing which is located axially between the gear portion of the output gear and the dam.
According to another aspect of the present invention, an automatic transmission comprises:
an output gear having a gear portion for delivering an output rotation of the automatic transmission, and a hollow boss;
a taper roller bearing having a plurality of tapered rollers arranged around the boss of the output gear;
an inner rotating shaft received inside the boss of the output gear and formed with a lubricating oil passage; and
an outer non-rotational annular portion surrounding and supporting the taper roller bearing; and
a dam forming an oil reservoir for storing a lubricating oil supplied from the oil passage in the inner rotating shaft, the dam extending from the annular portion radially inwardly to a projecting dam end located on an imaginary cylindrical surface which passes through the tapered rollers.